Soft viscoelastic robot skin capable of accurately sensing contact location of object

The study concerns development of a robot skin which is capable of accurately sensing the contact location of an object, taking advantage of the soft skin surface made of gel which allows the skin to make an areal contact with the object. There has been no report on tactile sensing which attained not only skin deformation detection but also contact object location sensing of high accuracy. First, we show in the paper the structure of the robot skin, with 15 tiny reflector chips arranged in a matrix form on the skin surface. Second, we describe the principle of sensing the contact location of an object-both optically detecting the positions of the reflector chips which corresponds to the deformation of the skin surface of gel being pressed by an object and fitting the planes of the object from the deformation data assuming the object to be a convex polygon. The robot skin is characterized by a skin surface which is low in cost and easily replaceable, and the sensing performance is robust against any electromagnetic disturbance. Third, we report some experiments conducted for verifying the above principles as well as accurately detecting the position of the reflector chip from which the covariance matrix of detection errors was computed, and sensing the location of a wedge-shaped object. For evaluating the accuracy, comparisons are made between the real convex angle of the object and the estimated polygon, as well as between the real motion of the object and the estimated motion.